1. Field of Invention
This invention relates to a glass run fit into a door sash of an automobile and for guiding a descending or ascending door glass.
2. Description of Related Art
In an automobile, a C-channel type glass run 5 is generally fit into the door sash 2 of a car door 1 for the purpose of guiding a descending or ascending door glass 3 into the groove 4, as shown in FIGS. 6 and 7. In particular, a connector 5B is provided in the corner of the door sash 2 in order to connect two straight glass runs 5A along the frame of the door window. In general, the straight glass runs 5A are formed by extrusion, while the connector 5B is formed by molding.
The glass run 5 comprises an outer wall 6, a bottom 7, and an inner wall 8. The glass run 5 has a U-shaped cross-section, which forms a groove 4 in it. An outer lip 9 extends inward from the outer wall 6. This outer lip 9 comes into contact with the outer surface of the door glass 3 when the door glass 3 ascends. Similarly, an inner lip 10 extends outward from the inner wall 8, which comes into contact with the inner surface of the door glass 3. Also, outer mole lips 11 and 12 extend outward from the outer wall 6, while inner mole lips 13 and 14 extend inward from the inner wall 8.
However, due to the structural limitation of a molding die used in the molding process of the connector 5B of the glass run 5, the outer wall 6 inevitably opens outward by an angle .theta.1 with respect to the normal to the bottom wall 7, while the inner wall 8 inevitably opens inward by an angle .theta.2 with respect to the normal, as shown in FIGS. 7 and 8. This occurs because a center core is required in the molding process, which turns out as the gap L between the outer lip 9 and the inner lip 10. FIG. 8 illustrates the glass run 5 shown in FIG. 7 viewed from the bottom faces of the outer and inner lips 9 and 10.
If this glass run 5 is fit into the door sash 2, a strain is caused in the molded connector 5B due to the small gap L between the outer and inner lips 9 and 10. As compared with the ideal connector which has no gap L between the outer and inner lips (that is, which has the outer and inner walls parallel to each other without angular deviation), the peripheral length of the corner part of the connector 5B having a gap L between the outer lip 9 and the inner lip 10 becomes slightly longer. This excessive length centers on the middle of the corner of the connector 5B, which causes distortions in the outer and inner walls 6 and 7. The distortion caused in the outer wall 6 is due to the angular deviation of .theta.1, while the distortion caused in the inner wall 8 is due to the angular deviation of .theta.2.
Such distortions cause the lips to be pushed inward or outward, and the direction of deformation is uncertain. If the inner wall 8 is pushed outward by the strain, the inner lip 10 is also pushed outward, as shown in FIG. 9, and it comes into tighter contact with the door glass 3. In this case, there is no serious problem. However, if the inner wall 8 is pushed inside the car, as shown in FIG. 10, the airtight contact between the inner lip 10 and the door glass 3 is loosened, and a draft noise is generated from the air gap between the door glass 3 and the inner lip 10.
Similarly, if the outer wall 6 is distorted inward, the outer lip 9 is pushed inward, which enhances the contact with the door glass 3. However, if the outer wall 6 is distorted outward, the outer lip 9 is pushed outward, which deteriorates the sealing ability of the outer lip 9. Thus, the airtight contact between the outer lip 9 and the door glass 3 is not maintained any longer.